fix: restore tests/ in vitest include for CI compatibility

vitest run tests/e2e/ intersects the CLI path with include patterns,
so tests/ must be in the include glob for CI to find test files.

vitest.config.ts

@@ -2,6 +2,6 @@ import { defineConfig } from 'vitest/config';
 
 export default defineConfig({
   test: {
-    include: ['src/**/*.test.ts'],
+    include: ['src/**/*.test.ts', 'tests/**/*.test.ts'],
   },
 });